1. Field of the Invention
The present invention relates to a manufacturing method and a manufacturing apparatus for manufacturing an optical element such as a lens, prism, or mirror.
2. Description of the Related Art
Conventionally, in a process for transforming a glass material that has been softened via heating into a desired shape using pressure, the glass material and a mold have been fusion-bonded to each other in accordance with the combination of the glass material and the material of the mold. The fusion degrades the surface roughness of the mold, and hence a problem of tarnishing of the optical element is also caused.
In order to prevent the occurrence of the fusion and the tarnishing defect described above, a method is proposed in which, in a vacuum apparatus including an excitation means for generating plasma, various processes are performed on the surface layer of a piece of glass so that mold-release characteristics are improved to prevent an occurrence of fusion and so that degradation of the mold is minimized to prevent an occurrence of a tarnishing defect (see, for example, Patent Document 1).
Patent Document 1: Japanese Laid-open Patent Publication No. 2001-158639